Lehr loaders, or stackers as they are sometimes termed, basically transfer a row of newly formed glass bottles that are moving at right angles to the movement of a lehr mat from a cross conveyor that is supporting the bottles by pushing the bottles sideways from the conveyor onto the end of the moving lehr mat. This transfer motion has to be coordinated with both the conveyor motion and lehr mat movement. The lehr has the function of annealing the bottles to remove any stress or strain in the glass. Where articles are produced in large quantities, it is most desirable, for efficient operation, that article handling be performed mechanically and preferably this means that the ware should be smoothly and automatically handled from the time that the ware is set out, from the forming machine onto a machine conveyor, to when the ware is transferred to a cross-conveyor. The cross-conveyor moves across the width of the lehr at the front end thereof and it is from this crossconveyor that the lehr loader or stacker moves the newly formed ware into the lehr.
In the operation of the prior art lehr loaders, where the bottles are slid from the cross-conveyor, over a dead plate and onto the lehr mat, there is a certain amount of scuffing of the bottom of the bottles. Scuffing is not a desirable attribute to bottle handling and may result in the unannealed bottle being "checked" in its bottom surface. Side engagement by a lehr bar also may cause thermal checking of the lower side of the ware when it is contacted by the metal or graphite bar. The operations of the loader, conveyors, and lehr mat must be synchronized to assure proper handling. There also is a danger of the ware contacting each other during transfer or tipping of the ware while sliding onto the lehr mat. The typical cross-conveyor is traveling at a much faster rate than the lehr mat and this distinct differential can be a defect producing situation when the forming machine is producing as many as or more than 480 bottles per minute, the nominal rate for a 10-section, quadruple cavity I.S. machine.
An example of the bottle side engaging lehr loader is disclosed in U.S. Pat. No. 4,067,434, dated May 13, 1976.
It has been suggested that the bottles may be transferred by vacuum cups which will seat on the finish of the container and lift the bottle by its neck. One problem with this sort of system is that there is a great tendency for the bottles to swing and contact each other, particularly when the bottles must be picked up and moved from the cross-conveyor at a rapid speed and then the line must be slowed down to the speed of the lehr mat when the bottles are lowered and released onto the mat. This would obviously be more pronounced when dealing with narrow-neck bottles such as used for wine and beer. Since many narrow-neck bottles are tall with small diameter necks relative to their mass grasping by the neck will create a swinging moment of inertia that acts from a point at the top of the bottle. The bottles will invariably contact each other and produce defects if the movements are rapid enough to handle the ware at the forming speeds encountered today.
When using the vacuum cup transfer where the neck is sealed by the cup, one problem is that the vacuum lifting force is supplied by the neck area only and for most bottles this will require a vacuum source of 700 to 1000 MM of water from vacuum pumps that are expensive to maintain.
A second problem with the prior art vacuum bottle transfer system is that of maintaining a seal between the line contact area of the bottle neck or finish and the vacuum cup. Most high temperature materials will rapidly wear at the finish surface contact area requiring frequent replacement and constant vigilance.
With the foregoing in view, the present invention provides a hot bottle transfer system where the bottles are picked up by a vacuum transfer bar, elevated and rapidly moved without danger of thermally shocking the bottles yet providing smooth transfer at the preselected speeds. The bottles at the time they are to be transferred may have a temperature in the range of 200.degree.-232.degree. C.